1. Field of the Invention
The present invention relates to a method and an apparatus for adding water to a photosensitive material processor, and more particularly to a method and an apparatus for adding water to a photosensitive material processor to keep constant the concentrations of processing solutions stored in processing tanks.
2. Description of the Related Art
An automatic processor, i.e., a kind of photosensitive material processor, is provided with processing tanks such as a developing tank, a bleaching tank, a fixing tank, a washing tank, and a stabilizing tank. A developing solution, a bleaching solution, a fixing solution, washing water, and a stabilizing solution (hereafter, these solutions and water will be generally referred to as the processing solutions) are stored in the respective tanks. The photosensitive material subjected to print processing is consecutively immersed and processed in the processing solutions in the respective processing tanks, and is then dried in a drying station disposed downstream of a final processing tank and is taken out.
Since the replenishment of replenishers in the respective processing tanks is effected in correspondence with the amount of the photosensitive material processed and the like, the compositions of the processing solutions are kept constant. With respect to the loss of the processing solutions due to evaporation, however, only the water in the processing solutions decreases, so that the concentrations of the processing solutions change, thereby deteriorating the processing performance. For this reason, in order to maintain the original concentrations of the processing solutions, it is necessary to add water corresponding to the evaporated portions separately in addition to the replenishers. However, the amount of evaporation differs depending on the surrounding environment, i.e., the ambient temperature and humidity, and it also differs depending on whether the apparatus is running, is on standby, or is resting. Hence, it is impossible to univocally set the amount of evaporation through calculation and the like.
For this reason, there has been proposed a technique in which a level sensor such as a float is provided in each processing tank, and water is added on the basis of the detected value of each level sensor (for example, see Japanese Patent Application Laid-Open No. 281446/1989). With the level sensors, however, components of the processing solutions can be deposited and adhere to the floats, thereby possibly leading to erroneous detection of the solution level. Hence, the level sensors have low reliability, and there are cases where it is impossible to effect addition of appropriate amounts of water. This also holds true of the case where a concentration sensor (densimeter or the like) is used, and these level sensors and concentration sensors are high in cost, and therefore lack practicality.
In addition, there has been proposed a technique in which monitoring processing tanks are provided in addition to actual processing tanks, and water is added to the actual processing tanks on the basis of the degrees of evaporation of the processing tanks (refer to Japanese Patent Application Laid-Open Nos. 254959/1989 and 254960/1989). According to this technique, it is possible to obtain data which is equivalent to actual amounts of evaporation, so that the reliability improves. However, since the above-described water adding system requires the monitoring processing tanks in addition to the actual processing tanks, there are problems in that the apparatus becomes large in size, and that the number of components used increases. In addition, there is a problem in that management and maintenance for maintaining the monitoring processing tanks under conditions equivalent to those of the actual processing tanks become complicated.
To overcome the above-described problems, there has been proposed a water adding method in which an ambient condition such as a wet, standard, dry, or other similar condition is determined, a coefficient of correction fi of an amount of water to be added is determined by estimating the speed of evaporation of water from the processing solution on the basis of the ambient condition determined, thereby to determine the amount of water to be added (refer to Japanese Patent Application Laid-Open No 4-1756). In this water adding method, it is possible to obtain outstanding advantages in that highly reliable, appropriate amounts of water to be added can be obtained without using special equipment such as the monitoring processing tanks for obtaining the amounts of water to be added, i.e., amounts of evaporation of water, and that the efficiency in management and maintenance can be improved.
With the above-described water adding method, however, it is necessary for the operator (or a servicer of the manufacturer) to determine the ambient condition, such as the wet, standard, dry, or other similar condition. In general, the operator determines the ambient condition by measuring the temperature and humidity, but skill is required in estimating the speed of evaporation of water from the processing solutions on the basis of the temperature and humidity. If the operator does not have knowledge about evaporation, there is a possibility that he or she may make an error in determining the ambient condition. For instance, in the case of the ambient condition where the temperature is 25.degree. C. and the humidity is 35%, if a comparison is made with the ambient condition where the temperature is 15.degree. C. and the humidity is 65%, the speed of evaporation of water from the processing solutions is practically the same. Yet, since the humidity is 35%, there is a possibility of the ambient condition being determined as "dry."
In addition, in automatic processors, replenishers for the processing solutions are replenished in proportion to the amounts of the photosensitive material processed, the amount of oxidation due to air, and the like. For this reason, in the automatic processors in which the amount of the photosensitive material processed is large, large amounts of replenishers are replenished relative to the amounts of evaporation from the processing solutions, and the processing solutions do not undergo large variations in the concentration even if the aforementioned determination of the ambient condition is mistaken. However, in the automatic processors in which the amounts of the photosensitive material processed is small, small amounts of replenishers are replenished relative to the amounts of evaporation from the processing solutions, so that the concentrations of the processing solutions increase more rapidly. In this case, an erroneous determination of the ambient condition results in a substantial change in the concentrations of the processing solutions, thereby exerting a large influence on the finishing quality and the like in the processing of the photosensitive material.
In addition, recent automatic processors are designed to consume less amounts of replenishers per predetermined amount of photosensitive material processed (e.g., the amount of replenishment per film is less than half the conventional level). As the automatic processors requiring less amounts of replenishers, it is possible to cite, among others, the CN-16FA (trade name) made by Fuji Photo Film Co., Ltd., the C-41RA (trade name) made by Eastman Kodak Co., and the CNK-4-52 (trade name) made by Konica Corporation. With such automatic processors as well, the amounts of evaporation from the processing solutions remain practically the same as before, and the amounts of replenishers with respect to the amount of evaporation from the processing solutions are small. Hence, in the event that an error is made in the determination of the ambient condition, a large influence is exerted on the finishing quality.